Computational plasticity of mixed hardening pressure-dependency constitutive equations
Until now, two fully explicit exponential-based integrations have been presented for the mixed hardening Drucker-Prager's constitutive equations, which are a widely used plasticity model to predict the elastic-plastic behavior of a broad range of geotechnical materials such as rock, soil, concrete as well as iron-based substances, including aluminum and porous metals. In the present paper, it is desired to improve the integration schemes by converting them into semi-implicit strategies. Two semi-implicit schemes, based on exponential maps method are derived for integrating the pressure sensitive constitutive equations. In addition, the consistent tangent operators, which are necessary for the implicit finite element codes, were derived for all the fully explicit and semi-implicit schemes. Further, the consistent tangent operator for an accurate integration was given. To evaluate the accuracy, the numerical investigations consisting of the strain load histories, iso-error maps and boundary value problems were taken into account. It was shown that the semi-implicit methods have second order accuracy compared to the first order precision of the fully explicit schemes. As a result of the boundary value problems has demonstrated that the efficiency of the finite element analysis, when the semi-implicit stress updating algorithms are used, is much higher than that of those which the filly explicit algorithms. The correctness of the derived constant tangent operators was also proven.
presure-dependency constitutive equations
scientific article; zbMATH DE number 6306008
scientific article